Increasingly, motor vehicles are being equipped with driver assistance systems, which support and relieve the load on the driver of the motor vehicle. Examples of such assistance systems include the ACC system (adaptive cruise control) for speed control or a PSS system (predictive safety system) for farsighted vehicle control, which may include, for example, a PBA system (predictive brake assist) for farsighted brake support, or a PEB system (predictive emergency braking) for farsighted brake activation.
Such driver assistance systems require sensors, with the aid of which the surroundings of the motor vehicle is able to be scanned for objects which could require influence on braking. Such sensors may include the processing of measured data, or the provision of raw data that are processed at a different location. Radar sensors, lidar sensors, ultrasonic sensors and optical sensors may be used individually or in combination with one another, for different distance ranges or directional ranges.
When several sensors are used (also of different technologies) it is possible to improve the accuracy and/or the integrity of the determined position of the object; based on redundant data. German Patent Application No. DE 101 49 115 A1 describes a technique for checking object measurements, carried out by several sensors, for consistency.
The sensors used are usually connected rigidly to the motor vehicle, and are thus safeguarded from misalignment (rotation with respect to the motor vehicle. A gradual misalignment with respect to the motor vehicle, that is progressive over a longer period of time, is improbable according to past experience. However, the misalignment of a sensor may occur, for example, by a relatively slight influence of an external object on the motor vehicle or its attachment parts, perhaps by a light collision, which may take place during parking or leaving a parking space. If a sensor is misaligned, the accuracy of the determination of the position of the object may be impaired, so that, under certain circumstances, a postconnected driver assistance system is not able to fulfill its task satisfactorily or at all.
Conventional techniques for detecting the misalignment of a sensor on a motor vehicle, and for compensating for it are available. Many of these techniques require an extensive learning phase, so as reliably to detect a misalignment of a sensor that has occurred.